1. Field of the Invention
The present invention relates to a video-signal switching apparatus, and more particularly, relates to a video-signal switching apparatus capable of switching two video signals at high speed.
2. Description of the Related Art
As one example of the conventional video-signal switching apparatus, for example, there is disclosed that which is mentioned in Patent Document 1. As shown in FIG. 12, a video-information editing apparatus mentioned in Patent Document 1 is composed of a decode determining unit/decoding unit 51, a control unit 52, and a re-encoding unit 53. The decode determining unit/decoding unit 51 is input video signals (A) and (B) to be edited and cutout position information (C). Then, the decode determining unit/decoding unit 51 decodes the cutout position and a picture (frame) near that position, and transmits attribute information (p), such as a picture mode, a bit amount, a quantization parameter, to a control unit 52. Upon receipt of the attribute information (p), the control unit 52 evaluates a correlation value of pictures at the cutout positions of the video signals (A) and (B). When the correlation value is equal to or more than a threshold value, the control unit 52 determines to encode the picture at the cutout position of the video signal (B) as an inter-picture that is the same as the picture at the cutout position of the video signal (A). On the other hand, when the correlation value is smaller than the threshold value, the control unit 52 determines to encode the picture at the cutout position of the video signal (B) as an intra-picture. Further, the control unit 52 determines whether it is possible to maintain a predetermined quality in relation to a bit amount of encoding when the re-encoding is performed by the determined encoding mode, and in response to the determination result, the control unit 52 analyzes to correct a picture type and an encoding amount of a plurality of frames before and after the cutout position of the video signals (A) and (B). Then, the control unit 52 outputs control information (q) (picture mode, quantization parameter, etc.) about each frame to be reconstructed, etc., to the re-encoding unit 53. The re-encoding unit 53 edits to switch between the video signals (A) and (B) based on the control information (q), and informs the control unit 52 of corrected process information (r) (virtual buffer occupation amount information, a bit amount, etc.). In this way, from the re-encoding unit 53, an edited video signal (E) is output.
According to the above-described conventional technology, it is possible to provide an effect in which an image quality degradation can be inhibited while suppressing an increase in the bit amount that occurs concurrently with re-encoding.
Patent Document 1: Japanese Published Unexamined Patent Application No. 2006-287444
However, in the above-described conventional technology, the video signal (B) succeeding to the cutout position is input, and thereafter, the control unit 52 evaluates the correlation value of the pictures at the cutout positions of the video signals (A) and (B). Based on the correlation value, a policy for re-encoding a plurality of frames before and after the cutout position is established, and in this state, the actual re-encoding is performed. Thus, there is a problem that a great delay between inputting and outputting of the video signal occurs.